Currently, aluminum sheet producers often use a cold rolling mill to produce sheet of a desired thickness, width and surface. Skin/temper rolling mills may also be used with low reductions (<10%) to produce desired surfaces. The surface of the cylindrical rolls (work rolls) through which the sheet aluminum passes may be prepared for a rolling operation by grinding with an abrasive grinding wheel or belt. Grinding leaves the roll surface with directionality in appearance and frictional properties due to grinding marks (grain), which are then transferred/imparted to a sheet that is rolled by the ground work roll. The directional appearance of sheet rolled by ground work rolls is visible and frequently can be seen through painted coatings applied to the sheet material or to products made from the sheet material, such as an automobile body panel.
Embossing mills are also used to impart a given surface topography on sheet metal, e.g., to produce non-directional topographies. Processing sheet in an embossing mill is conducted after the rolling process and after the sheet has been reduced in thickness to target dimensions that approximate the final dimensions of the sheet. Embossing mills are intended to impart surface texture only, as opposed to having a substantial sizing effect on the sheet, and therefore operate on sheet that has already been rolled by the work rolls of a rolling mill. Embossing sheet in an embossing mill represents additional steps beyond rolling, requiring additional apparatus, material handling and managing a greater variety of roll types compared to normal rolling mills.